The invention relates to a gearshift device for the shifting of gears, control pistons or the like. Such a device can be used, for example, for an auxiliary output drive found on commercial vehicle gear units, or for use in operating control pistons.
When connecting an auxiliary output drive to the gearshift device it is conventional to use a shift lever which is attached to the forward end of a rocking shaft. On the opposite end of the rocking shaft there is provided a lever element which projects from the gearbox casing, and to which is engaged a pressure-operated cylinder which causes the rocking of the shaft together with the shift lever. The cylinder is screwed firmly to the outside of the gearshift box through an attachment plate. This attachment plate, depending upon the position of the auxiliary output drive in the gearshift box and the kind of the auxiliary output drive, has different forms and must also have different positions on the gearbox. As a result, depending upon where the gear unit is built, examination must be made in advance to determine whether the cylinder, rocking shaft, the shift lever and attachment plate can be arranged on the gearshift box in the usual manner or whether a new arrangement must be provided, for instance, by new attachment holes and possibly other attachment plates and lever elements (see ANBAUANLEITUNG FUER NEBENABTRIEBE N 352/2, N 70/1, 2 or 3 from Zahnradfabrik Friedrichshafen, Inc.). It is also standard practice in the prior art to connect an auxiliary output drive to a gearshift device by means of a cylinder parallel to the shafts which are shifted together. In such gearshift devices the shift lever, which operates the shift sleeve, is directly and rigidly connected to the piston and, by connecting and disconnecting the piston, is slid into the respective final position, through which the shift sleeve is brought directly into the desired position in each case. As the cylinder, which is parallel to the shafts which shift together, is relatively long due to the necessary, relatively long shift path, much space is thus necessary in the longitudinal direction on the gear unit.
In the prior art of swing engines it is common to produce a swivel movement by means of a transverse cylinder so that the piston rod is formed as a gear rack in which the gear wheel meshes, the gear wheel being connected to the shaft to be swiveled. The use of gear wheel and gear rack is relatively costly, both with regard to production and the need for space. In addition, when the swivel element itself has no limiting stop to its path, there must additionally be a corresponding path limit provided by the cylinder. It is an object of the invention to provide a gear shift device which is simple and inexpensive in its manufacture and maintenance, and which can be integrated into the casing of the gearshift or alternatively be an independent, compact unit which can be attached to the gear shift box (or on the casing, for example, of a control valve) depending on particular requirements. The gearshift device of the invention also occupies a minimum amount of space, in particular, in the axle direction of the gear unit.